Earthquake · reviewed by a seismologist
M 1.7ml
Earthquake near Ontario, CA
No earthquake was likely felt in Ontario in the 24 hours to 5:18 am PST (13:18 UTC). The last one was M 1.7, 8 km (5 mi) SE, at 2:48 pm PDT on 9 October 2026, estimated intensity II (weak) in town. Every earthquake near Ontario
This page: a magnitude 1.7 earthquake was recorded 7 km (5 mi) east-southeast of Ontario, CA, at 3:10 pm PDT on 19 July 2023 (22:10 UTC), 9.5 km deep.
USGS: 5km ESE of Ontario, CA
in Ontario, CA · 77 km (48 mi) E of Los Angeles, CA
- When
- 3:10 pm PDT on 19 July 2023 ()
- Where
- 7 km (5 mi) east-southeast of Ontario, CA · earthquakes near Ontario
- Magnitude
- M 1.7 (ml)
- Depth
- 9.5 km below the surface
- Felt
- no reports yet
- Nearest
- Orange County, 44 km SSW
- Nearest mapped fault
- Red Hill-Etiwanda Avenue fault, 9 km from its surface trace — near is not the same as on
- Status
- Reviewed by a seismologist
USGS · last changed by USGS · we first saw it 1212 days ago
Earthquake alerts for Ontario, CA
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Alerts are on for .
Not a warning. An alert comes after USGS publishes a quake, usually minutes after the shaking. For early warning use ShakeAlert, through your phone's Wireless Emergency Alerts or the MyShake app.
This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.
At this magnitude and depth, people at rest would likely notice it out to about 9 km (6 mi) from the epicentre. In Ontario, 7 km away, the estimate is intensity II (weak). Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.
Likely felt in: Ontario 7 km, intensity II · Rancho Cucamonga 8 km, intensity II · Eastvale 8 km, intensity II. Estimated for each town centre; each link is that town's own record.
How big was it?
This earthquake released about 12 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.7 would have released about 32 times as much.
- Mineral, Virginia 2011 M 5.8 1,200,000× the energy of this one
- Magna, Utah 2020 M 5.7 870,000× the energy of this one
- Around the size people start to feel M 3.0 78× the energy of this one
- This earthquake M 1.7 about 12 lb of TNT
Energy from the Gutenberg–Richter relation (log10E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.
For this area
The largest earthquake within 50 km since 2016 was M 4.5 on 2020-09-19 — about 16,000 times the energy of this one.
Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:
- 6.2 3 km SE of San Bernardino, California · 30 km E of this epicentre
- 6.0 The 1910 Lake Elsinore, California Earthquake · 41 km SSE of this epicentre
- 5.9 The 1987 Whittier Narrows, California Earthquake · 46 km W of this epicentre
- 5.8 The 1991 Sierra Madre, California Earthquake · 46 km NW of this epicentre
- 5.5 The 1990 Upland, California Earthquake · 16 km NW of this epicentre
Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.
Where
Epicentre 34.0388, -117.5763. Map © OpenStreetMap contributors.
Nearby places
| Place | Distance | Direction from the epicentre | |
|---|---|---|---|
| Orange County, CA | 44 km (28 mi) | SSW | earthquakes near Orange County |
| Los Angeles County, CA | 65 km (41 mi) | WNW | earthquakes near Los Angeles County |
| San Diego County, CA | 135 km (84 mi) | SSE | earthquakes near San Diego County |
Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.
Aftershocks so far
55 earthquakes have been recorded within 50 km since this one.
- 1.6 4 km SSE of Ontario, CA
- 1.6 7 km SSE of Home Gardens, CA
- 1.8 4 km SSE of Home Gardens, CA
- 2.0 3 km NW of Placentia, CA
- 1.6 6 km S of Loma Linda, CA
- 2.7 7 km ENE of Rancho Cucamonga, CA
- 2.5 3 km E of Devore, CA
- 1.9 3 km S of Loma Linda, CA
- 2.1 6 km NNE of Fontana, CA
- 2.1 6 km NE of Fontana, CA
- 1.6 5 km SSE of Home Gardens, CA
- 1.6 1 km SSW of Muscoy, CA
- 1.7 7 km SSE of Home Gardens, CA
- 1.5 3 km SE of Loma Linda, CA
- 1.6 7 km WSW of Calimesa, CA
Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of . QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.
On USGS
- The official USGS event page — the source of record for every value above
- Did you feel it? Report it to USGS — reports go to USGS, not to us
- ShakeMap for this event, when USGS has produced one
QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.